A stacked MCP (Multi Chip Package) obtained by stacking semiconductor elements in multiple stages so as to have a high capacity has become widespread in association with the multi-functionalization of electronic devices such as a smartphone and a tablet PC, and a film-shaped adhesive that is advantageous in the mounting step is widely used as an adhesive for die bonding in the mounting of the semiconductor element. However, regardless of a tendency of multi-functionalization in this manner, the operation of the electronic devices tends to be slower since the processing speed of the data is limited by the connection method of the semiconductor element using the current wire bond. In addition, power saving is also being desired since there is a growing need to use the electronic devices for a long time without charging them while keeping the power consumption low. From such a viewpoint, in recent years, semiconductor devices having a new structure in which the semiconductor elements are connected to one another not by the wire bond but by a through electrode for the purpose of further increasing the speed and saving the power have also been developed.
High capacity is still desired although semiconductor devices having a new structure have been developed in this manner, and the development of a technique that is able to stack semiconductor elements in more multiple stages has been promoted regardless of the package structure. However, stable thinning of the semiconductor element is essential in order to stack a greater number of semiconductor elements in a limited space.
Currently, in the step of grinding a semiconductor wafer for thinning the semiconductor element, it has become the mainstream to grind a semiconductor wafer in a state of being supported by pasting a support tape, so-called BG tape to the semiconductor wafer. However, the thinned semiconductor wafer is likely to warp by the influence of the circuit applied to the surface thereof, and the BG tape that is a deformable tape material becomes not possible to adequately support the thinned semiconductor wafer.
From such a background, a thinning process of a semiconductor wafer to use a silicon wafer or glass that is a harder material than the BG tape as the support has been proposed, and a material to stick a semiconductor wafer to a silicon wafer or glass of the support has been proposed. It is required as an important characteristic to such a sticking material that the semiconductor wafer after being ground can be peeled off from the support without being damaged, and the peeling method is intensively investigated in order to satisfy such a characteristic. Examples of the peeling method may include those utilizing the dissolution of the sticking material in a solvent, those in which the peeling properties are improved by decreasing the stickiness through heating (for example, Patent Literature 1), and those utilizing the fact that the sticking material is modified or eliminated by being irradiated with a laser beam (for example, Patent Literature 2). However, it takes time to dissolve the sticking material in a solvent, and thus the productivity is likely to decrease. In addition, in the method to decrease the stickiness through heating, it is concerned that the semiconductor wafer is adversely affected by heating, and also the method is poor in heat resistance and thus it cannot be used in the process application to form a through electrode. On the other hand, in the method to modify or eliminate the sticking material by irradiating it with a laser beam, the installation of expensive laser equipment is essential and a considerable investment is essential for the application of such a process.